Modeling Soil Phosphorus Levels and Phosphorus Leaching from Agricultural Land in the Netherlands

O. F. Schoumans* and

P. Groenendijk

Alterra, Green World Research, Dep. of Water and the Environment, P.O. Box 47, 6700 AA Wageningen, the Netherlands.

Abstract

Abstract

The contribution of nonpoint-source pollution of P leaching and P runoff from agricultural soils is very important, especially in those areas with intensive livestock production systems. Prediction of the impacts of fertilization reduction measures on P loads from agricultural soils to surface water requires a sound description of the accumulation of P. In this article an overview is given of the Dutch approach. The presented methodology has been developed for noncalcareous sandy soils in flat areas where P loss by subsurface runoff is the dominating pathway. Based on the kinetics of P sorption and desorption of these soil types, P accumulation in soils, and inorganic P concentrations in soil solution can be modeled. Furthermore, methods have been deduced to translate the description of soil chemical P processes into commonly used soil P tests. As a result of this interaction, soil P tests can be used as an initial approach to estimate the potential risk of P leaching and runoff from agricultural soils in noncalcareous sandy areas. The description of the kinetics of inorganic P reactions and the modeling of soil P tests have been implemented in the ANIMO model in addition to an organic P cycle that is related to organic C and N dynamics. With this model, the fixation and immobilization of P by soll components can also be assessed. As a result of annual losses by fixation, immobilization, and subsurface runoff/leaching, changes in soil P test values with time can be estimated.

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